This invention relates to a process for producing a bearing having internal lubrication grooves and to the bearing produced thereby.
In many bearing applications, it is desirable to provide grooves in either the outer surface of the inner bearing element or the inner surface of the outer bearing element in order to allow access to the bearing surface by lubricating materials such as oil. It is known to produce such lubrication grooves by molding or machining grooves into an existing surface of the inner or outer bearing elements.
U.S. Pat. No. 2,389,253, issued to T. L. Gatke, on Feb. 12, 1944, discloses a bearing element for use as a shaft bearing wherein the inner surface of the outer bearing element is molded under heat and pressure to include axially extending lubrication grooves. The bearing is manufactured in two parts or halves which are assembled together during installation. U.S. Pat. No. 2,348,274, issued to E. S. Aker, on Jul. 28, 1943, discloses lubrication grooves formed from a corrugated sleeve having longitudinally extending channels. This bearing is manufactured of a non-metallic moldable material formed over the carrier sleeve of a corrugated rigid material such as a metal.
In U.S. Pat. No. 4,189,985, issued to Bernard Harris, on Feb. 26, 1980, a cylinder is disclosed having a bearing surface, internal surface including spiral lubrication grooves which are formed during manufacture of the cylinder due to the nature of a seamless fabric used as a bearing liner. The formation of grooves in this bearing is dependent upon formation of small voids under certain conditions and using a certain weave of fabric which merge and form minute continuous spiral grooves for retaining a slight amount of lubricant.
A problem with existing processes for putting longitudinally extending lubrication grooves into a bearing is that they involve either machining or heat forming of the bearing parts. Where the bearing includes a filament wound structure, as for example, an outer bearing race formed of wound fiberglass filaments impregnated with resin, such processes are not well suited. For example, when a bearing outer race is sought having a self-lubricating liner such as a TEFLON fabric that forms the bearing surface the known processes are not practical. Machining will remove part of the TEFLON fabric leaving frayed edges along the grooves and fiberglass cannot be shaped by heat forming to provide lubrication grooves. In summary, known processes are complicated and costly, requiring machining of grooves into the inner surface of a bearing element, and when a filament wound structure is required special expensively configured forming mandrels are needed.
Therefore, in spite of extensive development in this field over many years, a simple reliable and reproducible process for producing filament wound bearing members having lubrication grooves on the inner surface of the outer bearing member is needed. More specifically, a process is needed that will avoid the necessity of elaborate and permanent configurations of special mandrels on which the filament wound outer race is formed and which will not require grinding or other post curing processing of the filament wound structure.